Testing & Quality#

Software testing is the discipline of verifying that code behaves as intended, catching defects early, and building confidence in change. This path covers the full spectrum of testing practices — from fast unit tests to load testing at scale.

What You’ll Learn#

This path takes you from testing fundamentals through advanced techniques:

Testing Philosophy — Why we test, testing models (pyramid, trophy, honeycomb), and building a testing culture
Unit Testing — Writing focused, fast tests with the AAA pattern, fixtures, and parameterization
Mocking & Test Doubles — Stubs, mocks, fakes, spies — when and how to isolate dependencies
Integration Testing — Testing real interactions with databases, APIs, and external services
End-to-End Testing — Browser automation, API e2e, visual regression, and accessibility testing
TDD & BDD — Test-driven and behaviour-driven development workflows
Property Testing & Fuzzing — Generative testing, invariants, and mutation testing
Performance Testing — Load testing, profiling, benchmarking, and SLO validation

Prerequisites#

Comfortable reading Python and JavaScript code
Basic understanding of functions, classes, and modules
Familiarity with command-line tools
Experience writing at least simple programs (any language)

Who This Is For#

Developers who write code but don’t yet write tests systematically
Engineers looking to move beyond “it works on my machine” confidence
Teams wanting to establish testing standards and culture
Anyone preparing for senior engineering roles where quality ownership is expected

How to Use This Path#

Each section is self-contained but builds on previous concepts. Start with Testing Philosophy to understand the why, then progress through unit → integration → e2e for the how. TDD/BDD and property testing offer alternative approaches. Performance testing rounds out the picture with non-functional quality.

Recommended time: 2–3 hours per section, plus hands-on practice.